1. The Field of the Invention
The present invention is related to methods and compositions for substantially reducing smoke emissions from rocket motors during operation. More particularly, the present invention is related to a low smoke producing liner formulation for use in bonding rocket motor propellants within rocket motor casings.
2. Technical Background
In the manufacture of solid rocket motors, several components have been found to be essentially required. First there must be an adequate rocket motor case. The rocket motor case forms the exterior of the rocket motor and provides the essential structural integrity. The rocket motor case is conventionally manufactured from a rigid, yet durable, material such as steel or filament wound composite.
Placed within the interior of the rocket motor case is the propellant grain. The propellant forming the grain is conventionally burned to form thrust within the interior of the rocket motor case. The formation of hot gases upon burning of the propellant, and the subsequent exit of those gases through the throat and nozzle of the case provide the thrust to propel the rocket motor.
A further important component of the rocket motor is a liner layer, which is typically disposed between the rocket motor case and the propellant grain. The liner layer essentially comprises an insulator and adhesive. The liner holds the propellant in place within the rocket motor case and assures that the propellant will not move relative to the case during the operation of the rocket motor.
It is important that the case be insulated from the burning propellant grain sufficiently that the heat generated by the propellant does not damage the case. The liner helps to perform this function. It is important, for example, that the propellant not burn through the rocket motor case. If this occurs, the rocket motor is likely to fail.
In addition, the liner performs the important function of confining the combustion of the propellant to the desired location within the rocket motor case. Often propellant grains are specifically engineered and configured such that they burn in a specific manner in order to provide the desired level of thrust throughout the operation of the rocket motor. If burning were to inadvertently occur between the case and the propellant grain, it would be possible for the rocket to experience undesirable and uncontrolled thrust during the operation of the motor.
Accordingly, it will be appreciated that the liner is an important component of the overall rocket motor. It serves a number of important functions. The liner acts as an adhesive, bonding the propellant grain to the casing. The liner also insulates the casing from the burning propellant and confines the ignition of the propellant to the desired location.
In some applications, it is important that the rocket motor perform with reduced or eliminated smoke output. Work is ongoing in the area of development of low smoke propellants. One problem that continues to be encountered in the production of "smokeless" rocket motors, however, has been the liner used. The burning of conventional liners during rocket motor operation produces significant quantities of smoke, even in motors which use smokeless propellants.
In many settings, such as in the use of tactical rocket motors, the production of smoke causes a number of disadvantages. The smoke produced may obscure the vision of pilots or drivers of crafts firing such tactical rockets. In addition, the production of smoke makes tracking the source of the motor easier, a serious disadvantage during military operations.
Accordingly, it would a be significant advancement in the art to provide methods and compositions for reducing smoke produced during the operation of rocket motors. More specifically, it would be an advancement in the art to provide a liner which produced relatively little smoke upon combustion of the propellant grain. It would be a further advancement in the art to provide such a liner which was also capable of securely bonding a variety of propellants within a variety of conventional rocket motors. It would be a further advancement in the art to provide methods for production and use of such liner formulations.
Such methods and compositions are disclosed and claimed herein.